The present invention relates to a method of transferring to a retroreflective pattern onto a fabric.
A known method of the type comprises a step of superposing on the surface of a fabric a retroreflective pattern transfer sheet comprising a base film composed of a plastic film (e.g. polyester film) having a thickness of about 10-50.mu., a mass of transparent fine glass spheres having a refractive index of 1.9 and a mesh size of 250-350, for example, and deposited on the base film, through a temporary holding (or peelable) adhesive composed of an epoxy resin having a dry thickness of about 8-15.mu., in microscopically spaced apart relation so that they are more than half exposed, a reflctive film layer consisting of a transparent colored film having a thickness of about 1.mu. or less, for example, and a deposited metal film (e.g. aluminum) and laid over the exposed surface of the transparent fine glass spheres and over the surface of the adhesive present at gaps between adjacent transparent fine glass spheres, and a coat of a hot-melt adhesive laid over the reflective film layer to provide a substantially flat outer surface, said superposition being effected through said hot-melt adhesive, a step of pressing the retroreflective pattern transfer sheet from the base film side through a hot convex form having a predetermined pattern engraved thereon, thereby melting a hot-melt adhesive portion corresponding to the convex pattern so that the corresponding portion of the retroreflective pattern transfer sheet is deposited on the surface of the fabric, and a step of applying a peel force to the retroreflective pattern transfer sheet so that at gaps defined by individual transparent fine glass spheres along a border line between one portion of the transfer sheet which is in bond with the fabric surface and another portion which is not in bond with the fabric surface, the hot-melt adhesive and reflective film layer are scissioned so that at the portion in bond with the fabric surface the base film is peeled off together with the temporary holding adhesive, a mass of transparent fine glass spheres less than half exposed being thus retained, together with the associated reflective film layer, on the surface of the fabric to form a retroreflective pattern portion on the fabric and so that the portion of the transfer sheet which is not in bond with the fabric surface is peeled off in its entirety. (Japanese Patent Publication No. 357 of 1977.)
In this known method, as above described, the step of peeling the retroreflective pattern transfer sheet is carried out in such form that at gaps between transparent fine glass spheres the hot-melt adhesive layer is scissioned. However, the trouble is that the hot-melt adhesive layer at such portion is thicker than at the other portion of the retroreflective pattern transfer sheet, so that the step of scissioning cannot be smoothly carried out. In some cases, at a portion not in bond with the fabric surface the base film may be peeled off together with the temporary hold adhesive in same manner as at the portion in bond with the fabric surface, with the result that a somewhat deformed retroreflective pattern may be produced on the fabric.
Another difficulty with the known method is that the exposed surface area (exposed height or angle) of the transparent fine glass sphere that determines the luminance of the retroreflective pattern is governed by the depth to which the glass sphere is embedded into the temporary holding adhesive, which fact makes it practically impossible to vary the luminance of the retroreflective pattern, and more particularly to provide a retroreflective pattern having different luminant intensities as desired from the standpoint of visual richness.